1. Field of the Invention
This invention relates generally to signal processing systems, and relates more particularly to a system and method for preventing artifacts in an audio data encoder device.
2. Description of the Background Art
Implementing an effective and efficient method of encoding audio data is often a significant consideration for designers, manufacturers, and users of contemporary electronic systems. The evolution of modern digital audio technology has necessitated corresponding improvements in sophisticated, high-performance audio encoding methodologies. For example, the advent of recordable audio compact-disc devices typically requires an encoder-decoder (codec) system to receive and encode source audio data into a format (such as MPEG) that may then be recorded onto appropriate media using the compact-disc device.
Many portions of the audio encoding process are subject to strict technological standards that do not permit system designers to vary the data formats or encoding techniques. Other segments of the audio encoding process may not be altered because the encoded audio data must conform to certain specifications so that a standardized decoder device is able to successfully decode the encoded audio data. These foregoing constraints create substantial limitations for system designers that wish to improve the performance of an audio encoder device.
A paramount goal of most audio encoding systems is to encode the source audio data into an appropriate and advantageous format without introducing any sound artifacts generated by the audio encoding process. In other words, an audio decoder must be able to decode the encoded audio data for transparent reproduction by an audio playback system without introducing any sound artifacts created by the encoding and decoding processes.
Digital audio encoders typically process and compress sequential units of audio data called "frames". A particularly objectionable sound artifact called a "discontinuity" may be created when successive frames of audio data are encoded with non-uniform amplitude or frequency components. The discontinuities become readily apparent to the human ear whenever the encoded audio data is decoded and reproduced by an audio playback system.
Furthermore, to effectively encode audio data, the audio encoder must allocate a finite number of binary digits (bits) to the frequency components of the audio data, so that the encoding process achieves optimal representation of the source audio data. An efficient bit allocation technique that prevents discontinuity artifacts would thus provide significant advantages to an audio decoder device. Therefore, for all the foregoing reasons, an improved system and method are needed for preventing artifacts in an audio data encoder device.